Monthly Archives: June 2016

Continuing the series of sharing Carebundles, Alan Garner moves on to go through the stuff to include in multiple blunt trauma.

OK, part 2 in our Carebundle series. This time we will take a look at our multiple blunt trauma bundle. This excludes isolated head injury which we dealt with in the previous post. Why that order you may ask? Our Sydney service started life as a trial evaluating the management of severe head injury so TBI is front if mind for us. It is also more straightforward as there are not the competing priorities that occur in multiple trauma. And in the end we don’t just want survivors but neurologically intact survivors so starting with TBI and brain resuscitation makes sense. The multiple blunt trauma bundle has conditional targets that are modified by the presence or absence of brain injury acknowledging that brain resuscitation is our major goal.

So multiple blunt trauma is next. This has many bits of intrigue to it. It is multiple. We’re moving into the bits of the body where the pathology can be buried in the large splodgy bit in the middle. The diagnostic stuff can be pretty challenging at the side of the road. Oh, and because it’s multiple there’s always that threat of a new competitor emerging in the pathophysiology parade.

We won’t touch on penetrating trauma, burns and immersion all of which have their own bundles of joy for another time.

The Common Touch

All of the mandatory items overlap with the TBI bundle so we won’t waste any time on them here:

Venous access – yes we reckon that still makes sense.

Analgesia – opioids/ketamine – yes we’re really trying to stress that analgesia is a vital component of care, pretty much every time.

Monitoring: SpO2, NIBP, ECG

Spine immobilisation – note we’re just sticking with immobilisation.

SpO2 > 93% by ED arrival

Scene time < 25 min – again, this isn’t always possible which is part of why Carebundles provide guidance but need clinician judgment on each job. What we’re aiming for is a background enthusiasm for keeping momentum throughout the time we’re looking after patients so we can get them to the hospital with all those eager people waiting.

Transport direct to trauma centre – this would be the house for the eager people.

The conditional items however vary from the TBI bundle and we will now go through these.

Checking the Terms and Conditions

Long bone fractures splinted

There is no evidence I am aware of that this changes outcome but it is standard ATLS teaching and makes pain control easier. We carry lots of excellent drugs and the Carebundle makes a point of mentioning them but everything is easier if you manage the physical elements contributing to the painful situation. Really this is the original multimodal analgesia. It’s just that one of the modes is “physical things that stop hurting things from exercising a right to freedom of movement”.

Massive external haemorrhage controlled

There is strong cohort level data that this saves lives, although more so in the penetrating trauma context where it is more common. Certainly data from recent conflicts supports this as a primary aim of prehospital care. So we’re carrying tourniquets, dressings, chitosan gauze and granules (though the latter are more for penetrating wounds).

Right here seems to be a point to salute the wondrous quality of the shells of prawns.

TXA if episode of SBP < 90mmHg, or below normal for age

CRASH 2 inclusion criteria were felt to be a little vague to include in our bundle. After all the inclusion criteria in this study was any trauma patient who was at risk of haemorrhage. To make the bundle we felt the item needed to identify the cases where TXA really should have been given because the risk of life threatening haemorrhage is so high. There is some evidence that just a single episode of documented hypotension is enough to identify a group of very high risk patients so we adopted this as our criteria. As another mental trigger point, some of our team have expressed a process when they consider packed cell transfusion – “If I’m reaching for blood, I should reach for that drug.”

If shocked, SBP at ED arrival (refer fluid guideline)

No head injury: palpable central pulses/obeying command

With head injury: Palpable peripheral pulses, or SBP > 90mmHg / lower limit of normal for age

In setting our blood pressure targets we differentiated between those with and without head injuries. Without a head injury permissive hypotension is our strategy. With a head injury we adopted the lowest level identified in the Brain Trauma Foundation Guidelines i.e. SBP of 90mmHg as our target. This is lower than our target for isolated severe TBI where our target is a MAP of 90mmHg or SBP of 110mmHg (see the TBI bundle post for further details). That last modification is obviously for paediatric patients where the guidelines are a little harder to attach specific numbers to.

If GCS < 9:

Intubation and mechanical ventilation

EAM above JVP (head elevation)

ETCO2:

30-35mmHg if no chest trauma/shock

25-30mmHg if chest trauma/shock present

This is similar to our isolated severe TBI bundle but we finesse our etCO2 targets in the presence of other injuries that might affect the gradient between arterial and alveolar levels. There is some evidence that adopting a lower prehospital etCO2 target in patients with chest trauma and/or shock is reasonable as these patients have predictably higher gradients. My own personal experience is that in patients who have both chest trauma and shock the target needs to be even lower. I have achieved an etCO2 by ED arrival in the mid-twenties in patients where both these factors are present only to find the first blood gas reveals an arterial level in the 50s. I would certainly be interested in hearing other people’s experience on this one. Of course in our rapid response urban trauma work we don’t carry a POC blood gas analyser like we do in our interfacility transport operations. Actually measuring the arterial CO2 would be ideal but we don’t think this is practical for both time and weight reasons in our urban response service.

Thoracic decompression if hypoxic/shocked & clinical or US suspicion of pneumothorax

I don’t think this one is rocket science. Even if we know a pneumothorax is present on ultrasound we usually leave it alone if they are not compromised. If compromise is present however then we expect it to be decompressed.

If GCS <13, BSL documented

All patients with an altered level of consciousness get their blood glucose documented.

Pelvic binder if shock and:

possible AP compression / Vertical Shear injury or signs of pelvic #

We don’t expect pelvic binders to be placed prophylactically. There is no evidence to support such a practice. We do however think that binders are helpful on AP compression and possibly vertical shear type injuries and the patient is shocked.

So that is it for our multiple blunt trauma bundle. It’s what we came up with on a review of the evidence but we’re always open to clever thoughts from others. If you have comments or suggestions we would love to hear from you.

And next time we return to the Carebundles it might just be time to get to the pointy end of penetrating trauma.

Notes:

As always, we’re very happy to hear other people’s clever takes on things that are worth doing. It helps us re-examine our thinking.

Here’s the PubMed link again for the “a single low blood pressure” matters paper linked above:

Sometimes really simple questions don’t get asked. Here’s a joint post from Alan Garner and Andrew Weatherall on places you end up when you ask simple questions about ways of warming blood.

Carriage of packed red blood cells (PRBC) by HEMS crews has become increasingly common in the last several years in both Europe and North America. CareFlight was an early adopter in this regard and has been carrying PRBCs to prehospital incident scenes since the 1980s. We reported a case of a massive prehospital transfusion in the 1990s (worth a read to see how much Haemaccel was given before we arrived on the scene and how much things have changed in fluid management). In that case we tried to give plasma and platelets as well but the logistics were very difficult. This remains the case in Australia with plasma and platelets still not viable in a preparation that is practical for prehospital use.

Returning to the PRBCs however the issue of warming them was something that always vexed us. We experimented with a chemical heat packs in the late 1990s and early 2000s but could not find a method that we felt was reliable enough. We also looked at the Thermal Angel device from the US when it appeared on the market nearly 15 years ago, but as the battery weighed the best part of 3kg we decided that it still had not reached a point where the technology was viable for us to be carrying on our backs (battery technology has moved on a long way in the last 10 years and Thermal Angel now have a battery weighing 550gms).

Fast Forward

Hence we were pretty excited when we found that there was a new device available in the Australian market, the Belmont Buddy Lite, where the whole set up to warm blood or fluid weighs less than a kg. We have been using the device for 3 years now, and our clinical impression was somewhere between impressed and “finally”.

Still, one of our docs, James Milligan, thought it worth validating this new technology. Part of that was about checking that the machine does what it says on the box. Is it just marketing or is it really that good?

The other thing we wanted to assess was how a commercial device compared to all those old techniques we were once stuck with. Traditional methods used by EMS in our part of the world include:

Stuffing the unit under your armpit inside your jacket for as long as possible prior to transfusion.

Putting it on a warm surface (black spine board in the sun or bonnet of a vehicle). Yep, baking.

That chemical heat pack method we had tried 10 years ago.

Some things aren’t a prehospital option. Well this isn’t anywhere maybe.

The Nuts and Bolts

Now, how would you go about testing this? The first thought bubble included a pump set, a theatres wash bowl and a standard old temperature probe that you might use at operation. Oh, and some blood. Like most bubbles that don’t involve property, it didn’t last long.

So we were left with a question: how do you try and set things up to test a system for the real world so it is actually like you’d use it in that real world, while still allowing measurements with a bit of rigour? How consistent are you when you deploy a blood-giving pump set?

Enter Martin Gill, perfusionist extraordinaire from The Children’s Hospital at Westmead. Because when we thought “how do we test prehospital blood warmers” obviously we thought about heart sugery in newborns. We turned to Martin with the following brief:

We want to test prehospital blood warming options.

We want to measure temperature really well.

We’re keen on being pretty rigorous about as many things as we can actually. Can we guarantee flow rate reliably?

We figure we could use units of blood about to be discarded and we want to be able to do the most with what we’ve got. So we want to be able to use a unit for a bunch of testing runs.

And Martin delivered. He designed a circuit (check the diagram) that would guarantee flow, measure in 3 spots, cool the blood once it had run through, and run it all through again. There are some things you could never come up with yourself. That’s just one.

It looks a little different in three dimensions but you get the idea.

You might wonder how hard is it to get blood? Well actually it was pretty easy (thank you Sydney Children’s Hospital Network Human Research Ethics Committee and Haematology at The Children’s Hospital at Westmead).

As you will note, the commercial warmer was the only method that reliably warmed the blood to something like a physiological level.

The change in temperature as the products pass through the line itself was more than we’d expected. Even the measurement of temperature just a little bit distal to the bag of blood showed a sharp step up temperature (that mean was 9.40C).

Any of the options that weren’t the commercially available device here guaranteed very cold blood reaching the end of the line. After all, 180C is the temperature we aim for when setting up deep hypothermic circulatory arrest in the operating suite. It is very cold. Should you even consider packed red blood cells if you aren’t going to warm them effectively?

In some ways, these aren’t super surprising items but small things like this can still be valuable. This was a humble little bench study of a simple question. Still, finding out that a device does what it says on the box by direct observation is reassuring. But …

We Have Questions

Research is very often an iterative process. Ask a question, provide answers to one small element of the initial puzzle, find another puzzle along the way and define a new question to explore. Each new question contributes more to the picture. On top of that, finding our way to the lab set-up and squeezing in the measurements around other work has taken a bit of time and things have moved along. This itself suggests new questions to ask.

Will everyone’s questions be the same? Well here are ours, so you tell us.

Now that we’ve come up with a lab set-up to test the manufacturer’s recommended use, what about testing a situation that more closely matches how the warming device is used at the roadside? As noted in the discussion, we don’t use machines pumping blood at a steady rate of 50 mL/min. How will a warmer perform at the much higher flow rates we demand in prehospital use? Will it still be a warmer or more of a tepid infusion system?

Are all devices the same? We didn’t choose the Buddy Lite because we were after a sweet, sweet money deal. It was the only prehospital fluid warmer with Therapeutic Goods Administration registration in Australia. There are now at least 2 other devices weighing less than 1 kg on the international market. They also advertise an ability to work at higher flow rates of up to 200 mL/min.

Are there are other potential problems when you warm the blood with these low dead space solutions? Let’s just imagine for a second you’re a red blood cell rushing through a warmer. In a pretty small area you’ll be put through a temperature change of over 200C within a system aiming to maximise that heat transfer in a very small bit of space. That implies the pressure change across the warming device could be pretty sizeable. When you get to the end of that little warming chamber having effectively passed through a very high pressure furnace, is there a chance you might feel like you’re going to disintegrate at the end of it all? What we’re alluding to is maybe, just maybe, does making red blood cells change temperature quickly while rushing through the system at up to 200 mL/min leave those red cells happy or is haemolysis a risk? If it was a risk, would the patient benefit from receiving smashed up bits of red cell?

Now that we’ve established a good model that will let us do rigorous testing,we can ask those new questions. Without the simpler first question, we wouldn’t be so ready to get going. Those new questions would seem to be how do modern devices perform at flow rates useful for the clinician rather than the marketing pamphlet? And what happens to the red cells in the process?

That’s the space to watch. Because that’s where we’re going next.

Notes and References:

Here’s the link to the prehospital massive transfusion case report mentioned near the start.

That image of the fire is from flickr’s Creative Commons area and is unaltered from the post via the account “Thomas’s Pics”.

And did you get this far? Good for you. Much respect to all those who read to the end of a thing. For this you get a reminder that you can follow along by signing up to receive updates when we post.

You also get the word of the week: colophon [kol-uh-fon] which is a publlisher’s or printer’s distinctive emblem used as an identifying device on books or other works. Alternatively it can be the inscription at the end of a book or manuscript.